API mail costs? Jobs draw on the meter.

By the USMail.ai team, more than 50 years of combined expertise in printing and mailing

Direct answer: Your integration signs in with OAuth to each USMail.ai account you register, at app.usmail.ai/mcp, and jobs it approves are paid from that account's meter balance. A person owns payment on each account: they set postage grant or Pay & Approve on the app, and nobody puts a password in a prompt.

These docs are for developers and companies that use USMail.ai MCP as the print-to-mail API in their own products and workflows. You register a USMail.ai account, or several, connect over OAuth, and then use the service like any other customer: your integration creates, uploads and proofs mail jobs and approves them once a person on the account turns on postage grant, and approved jobs are paid from the account's meter balance.

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How does the MCP account work?

A human registers on the app. Agents don't self-register, and there is no MCP-only user. One account owns the app and MCP, jobs the agent prepares show on the app for you to review, and you don't get a second queue. Register first if you don't have an account; the operator steps are on Getting started, and limits are on the MCP overview. USMail.ai is an AI print-to-mail platform: You upload. You approve. We produce. The AI suggests setup, such as mail class, paper and color. It never suggests addresses; you supply every address.

How is MCP mail paid for?

In the app, you pay per mailing or keep an optional meter balance. Agent approvals draw from your meter balance. Jobs from the app and jobs from an agent use the same account, and agents don't run card deposits.

Letters starting at $1.15, postage included. For a one-page, single-sided, black-and-white First-Class letter.

Paper, envelope and postage are on the job you approve. See how pricing works and what is included. Certified letters cost $1.15 plus the current USPS Certified Mail fee, and USPS tracking is included with every Certified letter. Certified is a mail class you choose before you approve, never an add-on. We don't offer paper Return Receipt yet.

Connecting doesn't spend, a proof doesn't spend, and with postage grant off, submit doesn't spend. A human turns on postage grant for the agent, capped or uncapped. With it on, the agent's submit approves a job within that limit, and the money comes from your meter balance. With it off, you review the job and Pay & Approve on the app. It isn't a monthly subscription; there are no contracts, subscriptions or setup fees. An approved job can be unapproved until its mail date. Unapproving puts the money back on your meter, not back on your card.

How does MCP sign-in work now?

The agent connects over OAuth at https://app.usmail.ai/mcp by signing in to your existing USMail.ai account (Connect / Authorize the usmail server). There is no separate key or token to copy, and you never put a password in a prompt. Use the USMail.ai Cursor plugin or Connect / Authorize the existing usmail server. After connecting, match the skills version to initialize.serverInfo.version, and don't add a second connector. Don't invent hostnames or install commands, and don't paste an install string from a blog. Live tool names come from the MCP server after you connect.

What is on the roadmap?

Today, sign-in is OAuth at https://app.usmail.ai/mcp, and billing runs on the same account as the app. Anything later is a direction, not a date, so don't build against credentials you weren't issued.

What happens if the meter balance can't cover the job?

Agent approvals draw from your meter balance, so an agent approval is rejected if the balance can't cover the job. There is no silent overdraft: production doesn't start until the job is paid. Add to the balance, or a human can Pay & Approve on the app and pay for that mailing. The agent can still prepare the job, and it can read the balance with the tools the server lists after connecting.

What are the security basics?

Only a human sets postage grant; with it off, a human does Pay & Approve on the app, Certified jobs included. Recipient data is production mail data, so handle it under your policies and don't paste recipient files into a public prompt. We will not ask for your password in an unsolicited call or email. Sign out on a shared computer. MCP is tied to your account, with no anonymous mailing. We check every address before mailing, and the AI never suggests an address; every address comes from you. USMail.ai is not USPS.

When does an approved letter go to USPS?

By default, letters you approve before 10 p.m. CT are handed to USPS the next business day. USPS delivery times vary.

What do people ask about USMail.ai?

Does MCP sign-in use a separate key?

No. MCP is OAuth at https://app.usmail.ai/mcp on your existing account. Connect / Authorize the existing usmail server, and never put a password in a prompt.

How do I pay for jobs an agent prepares?

In the app, you pay per mailing or keep an optional meter balance. Agent approvals draw from your meter balance. Postage grant caps what an agent can approve; with it off, a human does Pay & Approve on the app.

What happens if the meter balance can't cover the job?

An agent approval is rejected, and production doesn't start until the job is paid. There is no silent overdraft. Add to the meter balance, or a human can Pay & Approve on the app.

Do agents run card deposits?

No. A human manages payment in the app. Agents don't run card deposits.

Can an approved job be undone?

Yes. An approved job can be unapproved until its mail date. Unapproving puts the money back on your meter, not back on your card.

When does my letter go to USPS?

By default, letters you approve before 10 p.m. CT are handed to USPS the next business day (Monday to Friday). USPS delivery times vary. USPS handles delivery from there. There are no contracts, subscriptions or setup fees.

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